Wisconsin has historically been a turning point in presidential contests, and Democratic Sens. Barack Obama (Ill.) and Hillary Rodham Clinton (N.Y.) now have it clearly in their sights.

Obama was scheduled to fly to the Badger State Tuesday night for several events this week in advance of the Feb. 19 primary. He hopes a victory in Wisconsin could be pivotal to his campaign.

Clinton is also planning to attend a debate in the state, even as the Obama campaign continued Tuesday to decline participation. David Plouffe, Obama’s campaign manager, said Tuesday there had been plenty of debates already, and noted that two additional debates have already been scheduled.

So far, the Clinton campaign is ceding the advantage to Obama, but still hopes the New York senator will do well enough to pick off enough delegates to blunt any edge Obama might win.

The Clinton campaign said Tuesday afternoon that Obama enjoys the support of the state’s “political establishment” and a head start in Wisconsin. Mo Elleithee, a Clinton spokesman, said Obama got an earlier start in the state in terms of staffing, opening offices and going on the air with TV ads.

“Our goal there is to win our fair share of delegates,” Elleithee said.

Obama has a couple advantages in Wisconsin, the Clinton camp has noted. The state does not require party registration to participate in the primary, and with notable exceptions, Obama has done well with independent voters.

Obama “has some advantages in Wisconsin due to the open nature of the primary,” Mark Penn, the Clinton campaign’s senior adviser, acknowledged Monday.

Penn and campaign spokesman Howard Wolfson repeatedly said throughout a conference call Monday that February will be a better month for Obama than it will be for Clinton.

Obama’s campaign, however, sought to undercut the Clinton campaign’s efforts to lower expectations in the state, saying the high percentage of blue collar workers and absence of a caucus system should make it “prime turf for them.”

“Wisconsin’s going to be a real battleground,” Plouffe said.

Even if Obama wins handily, he is not likely to gain a clear lead in primary delegates over Clinton. A victory could, however, prove crucial in winning the support of Wisconsin superdelegate Sen. Russ Feingold (D), who hinted Tuesday that he might endorse one of the candidates if he or she wins the state by a large margin.